1# Environment Modes
2 
3Turborepo supports different modes for handling environment variables during task execution.
4 
5## Strict Mode (Default)
6 
7Only explicitly configured variables are available to tasks.
8 
9**Behavior:**
10 
11- Tasks only see vars listed in `env`, `globalEnv`, `passThroughEnv`, or `globalPassThroughEnv`
12- Unlisted vars are filtered out
13- Tasks fail if they require unlisted variables
14 
15**Benefits:**
16 
17- Guarantees cache correctness
18- Prevents accidental dependencies on system vars
19- Reproducible builds across machines
20 
21```bash
22# Explicit (though it's the default)
23turbo run build --env-mode=strict
24```
25 
26## Loose Mode
27 
28All system environment variables are available to tasks.
29 
30```bash
31turbo run build --env-mode=loose
32```
33 
34**Behavior:**
35 
36- Every system env var is passed through
37- Only vars in `env`/`globalEnv` affect the hash
38- Other vars are available but NOT hashed
39 
40**Risks:**
41 
42- Cache may restore incorrect results if unhashed vars changed
43- "Works on my machine" bugs
44- CI vs local environment mismatches
45 
46**Use case:** Migrating legacy projects or debugging strict mode issues.
47 
48## Framework Inference (Automatic)
49 
50Turborepo automatically detects frameworks and includes their conventional env vars.
51 
52### Inferred Variables by Framework
53 
54| Framework        | Pattern             |
55| ---------------- | ------------------- |
56| Next.js          | `NEXT_PUBLIC_*`     |
57| Vite             | `VITE_*`            |
58| Create React App | `REACT_APP_*`       |
59| Gatsby           | `GATSBY_*`          |
60| Nuxt             | `NUXT_*`, `NITRO_*` |
61| Expo             | `EXPO_PUBLIC_*`     |
62| Astro            | `PUBLIC_*`          |
63| SvelteKit        | `PUBLIC_*`          |
64| Remix            | `REMIX_*`           |
65| Redwood          | `REDWOOD_ENV_*`     |
66| Sanity           | `SANITY_STUDIO_*`   |
67| Solid            | `VITE_*`            |
68 
69### Disabling Framework Inference
70 
71Globally via CLI:
72 
73```bash
74turbo run build --framework-inference=false
75```
76 
77Or exclude specific patterns in config:
78 
79```json
80{
81  "tasks": {
82    "build": {
83      "env": ["!NEXT_PUBLIC_*"]
84    }
85  }
86}
87```
88 
89### Why Disable?
90 
91- You want explicit control over all env vars
92- Framework vars shouldn't bust the cache (e.g., analytics IDs)
93- Debugging unexpected cache misses
94 
95## Checking Environment Mode
96 
97Use `--dry` to see which vars affect each task:
98 
99```bash
100turbo run build --dry=json | jq '.tasks[].environmentVariables'
101```
102